In the construction and excavation industry, many kinds of equipment have been developed to assist the workers in their numerous tasks. One piece of equipment that has achieved nearly universal acceptance in the industry is the wheel or track-mounted tractor equipped with a hydraulic backhoe and bucket. These machines can perform a variety of jobs, including lifting, trenching, clearing and excavation.
Some construction jobs, however, require a backhoe tool that can grip or clamp material from both sides, rather than just move or "scoop" the material from one side. For example, the picking up and placement of logs or pipe is best accomplished with a tool that provides a clamping effort.
Several types of backhoe attachments have been designed to achieve this clamping effect. Typically, the standard backhoe bucket is replaced with a completely self-contained clamping system including a pair or "jaws" each actuated by its own hydraulic cylinder. Alternatively, a second hydraulically actuated jaw can be added on to an existing single bucket system. Such systems do indeed achieve the required clamping effect, but they are very costly in that they require a second hydraulic unit, and often render the original backhoe equipment unsuitable for standard trenching type operations. In addition, these attachments are often heavy and difficult to use, as well as highly vulnerable to damage.
Some backhoe attachment units have been developed which utilize a "stiff arm" portion which provides a fixed second jaw against which the movable backhoe bucket can clamp an object. However, these systems generally are limited in their range of motion, and hence have reduced application.